(R)-CMPD-39 is the R-enantiomer of CMPD-39. CMPD-39 acts as a selective non-covalent inhibitor of the ubiquitin-specific protease USP30 with an IC50 of approximately 20 nM and demonstrates high selectivity for other DUB family members at concentrations ranging from 1-100 μM. By inhibiting USP30's deubiquitination activity, CMPD-39 enhances the ubiquitination of mitochondrial proteins TOMM20 and SYNJ2BP and promotes the accumulation of phosphorylated ubiquitin. This process accelerates both mitophagy and pexophagy. Additionally, CMPD-39 significantly restores impaired mitochondrial function in dopaminergic neurons derived from Parkinson’s disease patients.